Evaluation of multisensory stimuli—Dimensions of meaning and electrical brain activity

Abstract

The semantic differential technique is used to statistically define connotative dimensions of meaning. The brain depends on these dimensions to process words. Earlier studies demonstrated that stimuli of the different semantic classes led to differences in neuronal processing. We investigated the influence of connotative meaning on multisensory processing (food words strongly related to odor, taste, vision or somatosensory texture). A group of 795 subjects rated 197 food words on the basis of 11 pairs of adjectives with opposite meanings. Factor analysis revealed three dimensions (Evaluation, Potency and Texture). Words with high positive or negative scores, and low scores on the other dimensions, were used as stimuli in an ERP experiment. EEG was recorded in 40 healthy adults from 30 channels and averaged according to semantic stimulus class.Component latency, global field power and topography were influenced by semantic meaning. These experiments determined that very early effects at 107ms after stimulus presentation where latency and GFP were affected by stimulus class. When mapped topographically, different stimulus classes led to different scalp topography of evoked brain activity in sagittal direction already at an early state of processing (around 107ms). The extent of lateralization of potential fields’ centers of gravity was influenced by stimulus class around 304ms.In summary, semantic dimensions influence neuronal processing of words related to multisensory perception. Such effects suggest a rapid and complex way of processing multisensory stimuli.